Weather Types Associated with Daily Intense Rainfall Events in The City of Recife - PE, Brazil

Abstract

The present study aimed to characterize the weather types associated with intense rain events in the city of Recife, by identifying both the frequency of these events and their dynamic mechanisms that explained their genesis. For this, local surface data were related to regional synoptic patterns. Principal Component Analysis and Hierarchical Cluster Analysis were applied to identify groups of homogeneous days in terms of hourly surface atmospheric data. For each group, the monthly frequency of intense rain events was presented and, from synoptic charts and satellite images, atmospheric patterns referring to the typical days were analyzed. Three groups of weather types associated with the occurrence of heavy rains were identified. Group 1 expressed 79% of the intense events (with highest record in autumn), group 2 corresponded to 9% of cases (with highest incidence in winter), and group 3 was 12% of intense rainfall (concentrated in summer and autumn seasons). The most frequent weather types were related to the displacement of barometric troughs in the trade wind fields, due to the strengthening of the easterly flow from the South Atlantic Semifixed Anticyclone. It is noteworthy that the intensity of rain events was explained by the interaction between synoptic circulation systems in meso- and local- scale.

Keywords:
Atmospheric Systems; Multivariate Statistics; Rainfall